A typical pulse encoder has a mechanical input, and is arranged to provide output pulses having a pulse rate which is dependent upon the rate of rotation of the mechanical input. Such a pulse encoder may be used in any of a wide variety of applications. For example, in a process which includes a conveyor, the mechanical input of the pulse encoder can be coupled to the conveyor so that the pulse rate of the output pulses provided by the pulse encoder is a function of the movement of the conveyor. One or more devices of the process are supplied with the output pulses of the pulse encoder in order to synchronize such devices to the movement of the conveyor.
One such component, for example, may be an ink jet printer which prints information on the articles being transported by the conveyor of the process. Where such articles are mail, the ink jet printer may be arranged to print addresses and other information on the mail being transported by the conveyor. In order to insure that the ink jet printer discharges its ink at the time that an envelope or other article of mail is in a position to properly receive the ink, the ink jet printer must be synchronized to the conveyor.
This synchronization is often provided by a pulse encoder. The mechanical input of the pulse encoder is coupled to the conveyor so that the pulse rate of its output pulses is representative of the speed of the conveyor. Thus, as the speed of the conveyor increases, the pulse rate of the output pulses provided by the pulse encoder increases, and as the speed of the conveyor decreases, the pulse rate of the output pulses provided by the pulse encoder decreases. The ink jet printer is connected to the pulse encoder so that the ink jet printer receives the output pulses of the pulse encoder and, thereby, is operated in synchronism with the mail being transported by the conveyor.
An ink jet printer of such an arrangement requires a predetermined number of pulses per inch of conveyor travel so that the ink jet printer is properly synchronized to the conveyor. Moreover, different ink jet printers require different predetermined numbers of pulses per inch of conveyor travel. Even the same printer may require different predetermined numbers of pulses per inch of conveyor travel if, for example, different fonts are to be printed. As a result, if a process includes a first ink jet printer, which operates at a first pulse rate, and if the first ink jet printer is replaced by a second ink jet printer, which operates at a second pulse rate, the resolution of the pulse encoder, i.e. the number of output pulses provided by the pulse encoder per inch of conveyor travel, must be adjusted to accommodate the second ink jet printer; or, if a printer of a process is to be operated at a new number of pulses per inch so as, for example, to permit the printer print a different font, the resolution of the pulse encoder must be adjusted to accommodate the new number of pulses per inch. An adjustment apparatus, therefore, is needed so that the resolution of the pulse encoderscan be made easily and rapidly in order to avoid prolonged disruptions in the operation of the process.
Furthermore, some processes include plural devices, such as ink jet printers, each of which must be synchronized to a conveyor of the process. If each device requires a different number of pulses per inch of conveyor travel for proper synchronization to the conveyor, and if the number pulses provided to each device per inch of travel of the conveyor of the process requires adjustment, an adjustment apparatus must be provided which accommodates the plural devices and which is arranged so that the number pulses provided to each device per inch of travel of the conveyor can be independently, easily, and rapidly adjusted.